1. Field of the Invention
The present invention relates to a scanning endoscope apparatus that acquires an image of a subject by scanning of illumination light having directivity.
2. Description of the Related Art
There has been proposed a scanning endoscope apparatus that acquires an image of a subject by irradiating illumination light to the subject with directivity and receiving reflected light while performing scanning in a direction of the illumination light.
For example, in a technique described in Japanese Patent Application Laid-Open Publication No. 2008-165236, an actuator is provided at a distal end portion of an endoscope and a distal end portion (12P) of an optical fiber is vibrated in a spiral manner. Further, a light refraction portion (12T) is provided in the optical fiber (12) behind the actuator (16) and slope surfaces (12X, 12Y) are formed on a cladding (12B). Further, a plurality of photo sensors (14) are provided around the optical fiber (12) behind the light refraction portion (12T), and a resin (19) having refractive index higher than that of the cladding (12B) is filled between the photo sensors (14) and the actuator (16). The reflected light that progresses in the cladding 12B exits from the slope surface (12X) and is made incident to the photo sensor (14). It is stated to thereby transmit light with high accuracy and to acquire information on an object by a simple construction.
In a technique described in Japanese Patent Application Laid-Open Publication No. 2011-55939, in an endoscope apparatus in which a probe (15) of a scanning endoscope is insertable into a forceps channel (10F) of a video scope (10), when a diagnostic mode is set, a normal observation image which is a full-color image and a fluorescence observation image are generated by alternately irradiating white light and excitation light, and a protruding length of a distal end portion (15T) of the probe and a bending angle (ω) of a distal end portion (10T) of an endoscope are detected. Based on the detected protruding length and the bending angle, an enlargement/reduction scale factor of a fluorescence observation image and an amount of phase shift are determined, and in a synthesis switching circuit (36) enlargement/reduction processing of the fluorescence observation image is performed in accordance with the determined scale factor so that a size of an observation subject such as an affected area coincides with a size of the observation subject in the normal observation image, and then phase shift processing is performed in accordance with the determined amount of phase shift. It is stated to thereby obtain a misalignment-free synthetic image between two images in the endoscope apparatus in which the probe can be used.
Further, in a technique described in Japanese Patent Application Laid-Open Publication No. 2010-117443, a scanning endoscope has a light supply fiber (53), a fiber drive section (54), and a top optical unit (60). The light supply fiber (53) emits light from an emitting end. The fiber drive section (54) bends the light supply fiber (53) from a first line (L1). The top optical unit (60) has first and second mirrors (61, 62). The first mirror (61) reflects light emitted from the light supply fiber (53) to the second mirror (62). The second mirror (62) reflects light reflected by the first mirror (61) in a direction including the first direction as a positive vector and going toward a point on the first straight line (L1). It is stated to thereby reduce distortion of an image in the vicinity of a center of spiral in a fiber-optic scanning endoscope which performs spiral type scanning
In the scanning endoscopes as described above, it is configured that a direction of a light emission end of the optical fiber which conducts the illumination light is changeable and the scanning of the illumination light is performed by changing the direction of the light emission end of the optical fiber as time elapses. On the other hand, the configuration for receiving light from a subject is made such that all the light from a scanning range of the illumination light can be received.
Accordingly, information indicating in which direction the received light comes (i.e. from which part of the subject the light comes) is not included in a signal generated by the received light. Therefore, configuration of an endoscopic image is performed by assuming that the received light is the return light from a part of the subject which is irradiated with the emitted light.
With the configuration of the conventional scanning endoscope apparatus as described above, an image of the subject can be precisely formed when there is not any external factor light (which is not return light of the illumination light emitted from the optical fiber, e.g. light generated by a treatment instrument for performing treatment on a subject with light emission, such as an electric knife and a medical laser) other than the return light from the subject within a light receiving range.